Leading Senior Constable Paul Marsland warned that there was no practice of NBN installers, internet providers or telcos calling households for legitimate purposes.

"If you receive a telephone call from anyone requesting your bank account details or online access hang up the telephone. Banks and utility or service providers do not do their business in this manner," he said.

The scam callers have convinced residents of problems with their NBN installation, internet modem and bank account access and offer to credit households a sum of money for repair.

"Through a system of dishonesty and trickery the criminals are obtaining from the victim their personal bank account details. While keeping the telephone conversation open a sum of money, larger than that indicated, is transferred into one of the victim's accounts by the scammer," Senior Constable Marsland said.

"This transaction is then identified by the scammer to be an error and requests that the victim transfer the money back to the scammer's account. In many instances this transfer is for many thousand dollars instead of the indicated small-value credit."

He said police were investigating a number of recent thefts linked to the scam, but investigations were particularly difficult to follow up or prosecute because transactions were directed to offshore accounts.

"Unlike fraud that is directed through credit cards or online banking it is less likely banks will take responsibility for this theft as the deception occurs between the scammer and the victim and is not a systems failure," Senior Constable Marsland said.

He encouraged residents to report any scams to police. Anyone with information can contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au

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